Demodulators – Frequency shift keying or minimum shift keying demodulator – Input signal combined with local oscillator or carrier...
Patent
1991-08-30
1992-08-18
Mis, David
Demodulators
Frequency shift keying or minimum shift keying demodulator
Input signal combined with local oscillator or carrier...
359192, H03D 300, H03D 904, H04B 1014
Patent
active
051402777
ABSTRACT:
For obtaining an output signal which is independent of the polarization direction of the received signal in a receiver for polarized electromagnetic signals, the received signal is split up into two components having a mutually orthogonal polarization direction before these signals are converted to an intermediate frequency. For combining, subsequent to demodulation, the two intermediate-frequency signals to a baseband signal which is independent of the polarization direction, a demodulator is used having a quadratic relation between input and output signals. For obtaining this quadratic relation, the intermediate-frequency signal is split up by an amplifier 20 into two signals having a mutually identical amplitude and mutually opposite signs. Consequently, the odd order terms in the sum of the currents through the diodes 27 and 28 will have opposite signs relative to the odd order terms in the sum of the currents through the diodes 36 and 37. By determining the sum of the currents through all four diodes, the odd order terms will cancel each other out so that only the even order terms of which the quadratic term is the most important will remain so that the desired quadratic relation is obtained.
REFERENCES:
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patent: 4577157 (1986-03-01), Reed
patent: 4972515 (1990-11-01), Shibutani
B. Enning et al., "Signal Processing in an Optical Polarization Diversity Receiver for 560-Mbit/s ASK Heterodyne Detection", Journal of Lightwave Technology, vol. 7, No. 3, Mar. 1989, pp. 459-464.
R. Modafferi, "A New Low Distortion FM Tuner", IEEE Transaction on Broadcast and Television Receivers, vol. BTR-16, No. 4, Nov. 1970, pp. 343-351.
Shibutani et al, "A Study on an Active Square-Law Combining Method for a Polarization-Diversity Coherent Optical Receiver", IEEE Photonics Technology Letters, vol. 1, #7, (Jul. 1989), pp. 182-183.
Hooijmans Pieter W.
Tomesen Markus T.
Barschall Anne E.
Mis David
U.S. Philips Corporation
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